Mother of James Potter and grandmother of Harry Potter (Pm).
Euphemia was surprised to discover she was pregnant rather late in life, after her husband had retired. They had a son, James, who they spoiled (Pm, JKR).
When James's friend Sirius Black was disowned by his family, Euphemia and Fleamont welcomed him into their home until he was able to find a flat of his own (OP6).
Euphemia and Fleamont lived long enough to see their son marry Lily Evans, but they died of Dragon pox before they could meet their grandson, Harry Potter (Pm).